The present invention relates to the management of data storage systems.
Corporations, academic institutions, governments, and other organizations store data in data storage subsystems. Each data storage subsystem typically includes a RAID controller that distributes data in disk arrays. Storage area networks (SAN) and Network attached storage (NAS) enable these organizations to locate data storage subsystems remotely in global enterprises to facilitate disaster recovery. Thus, the technologies and how they are employed distribute the data on many storage devices.
Efficient disaster recovery requires an accurate map of the data. System metadata (SMD) provides a map so the data can be potentially retrieved. Because the map is so crucial for data recovery SMD must be carefully protected. The SMD must be also updated when the data storage system is reconfigured, for example, to add or delete storage devices. Updating must be also executed completely or not at all to ensure consistency in the data storage system. Thus, SMD updates have the potential to tie up the host and adversely affect the network performance until they are completed.